The present invention relates to shaft components. More particularly, the present invention relates to a safety mechanism for reducing the likelihood of an improper shaft assembly connection.
Shafts are utilized in many applications and generally require interconnection between the shaft and a secondary component. The secondary component can be an independent component or a secondary shaft such that the shaft 20 serves as an intermediate shaft. In both instances, the forward end 22 of the shaft 20 is interconnected with a coupling element 10 which in turn is interconnected with the secondary component (not shown).
Many different coupling elements 10 can be utilized to connect the shaft 20 to the secondary component. One such coupling element 10 is a clamp yoke. An exemplary prior art clamp yoke is illustrated in FIGS. 1 and 2. The clamp yoke has a first portion 11 configured for secure connection to the shaft 20 and a second portion 13 configured for connection to the secondary component. The illustrated second portion 13 includes a yoke 18 extending from the first portion 11 with a securement bore 19 extending through the yoke arms. Other connection means may be utilized in the second portion 13.
The first portion 11 of the clamp yoke has a pair of side walls with a shaft receiving and retaining slot 12 extending therebetween. A retaining bolt 16 is passed through a through bore 14 in the side walls of the first portion 11 and tightened to secure the retaining slot 12 about the shaft 20. Furthermore, as a redundant safety feature, the shaft 20 typically has bolt receiving recess 24 in the form of a notch, an annular groove or other configuration adjacent the forward end 22 of the shaft 20. When the forward end 22 of the shaft 20 is first positioned in the slot 12 (as indicated by the arrow 1 in FIG. 1), the bolt receiving recess 24 is aligned with the through bore 14 and the retaining bolt 16 is slid through the through bore 14 and bolt receiving recess 24 (as indicated by the arrow 2 in FIG. 1) and secured by a cotter pin, nut or the like. The retaining bolt 16 extending through the bolt receiving recess 24 permanently secures the shaft 20 to the coupling element 10 first portion 11.
In many applications, for example, a steering intermediate shaft, the interconnection of the shaft 20 and coupling element 10 occurs in a location with limited accessibility. As such, it is difficult to visually or manually check that the retaining bolt 16 is properly received in the bolt receiving recess 24. For example, as illustrated in FIG. 2, the shaft 20 may not be fully inserted into the retaining slot 12 when the retaining bolt 16 is inserted. As a result, the retaining bolt 16 is not received in the bolt receiving recess 24. In some instances, the forward end 22 of the shaft 20 jams between the inserted retaining bolt 16 and the inner surface 18 of the coupling element slot 12 or, even if not jammed by the retaining bolt 16, the retaining slot 12 is tightened with only the very end 22 of the shaft 20 inserted in to the retaining slot 12. If the shaft 20 is jammed sufficiently or pinched at its very end 22, it may give a rigid feeling to an assembly worker, thereby creating a false sense that the shaft 20 is properly interconnected. After some use, the shaft end 22 may dislodge from between the retaining bolt 16 and slot surface 18 or may loosen from the minimal grip on the forward end 22, thereby causing disassembly and failure of the coupling.
FIGS. 1 and 2 show one prior art method utilized in an effort to minimize improper clamping of the shaft forward end 22. A counter bore 19 is provided about the retaining slot 19. While the counter bore 19 provides some effectiveness, it typically requires a secondary machining process which adds cost to the part. Additionally, the counter bore 19 may lessen the grip of the first portion 11 on the shaft 20 even when the shaft 20 is properly inserted.